Chip card with radio-frequency antennas

Abstract

A chip card including a card body including a metal layer, an RF chip, and a first RF antenna placed in a cut-out zone and connected to the chip. The metal layer has two regions, the first region completely containing the cut-out zone. A first slit connects the cut-out zone to an edge of the first region, a second slit opens onto an edge of the layer or into the cut-out zone and ends in the second region. A second RF antenna allows coupling to the first antenna. The chip card includes at least one turn facing the first slit and at least one turn facing the second slit.

The invention claimed is: 
     
         1 . A chip card comprising:
 a rectangular card body formed at least in part by a metal layer comprising a cut-out zone;   an RF chip;   a first RF antenna placed in or facing the cut-out zone and electrically connected to the RF chip,   said metal layer consisting of a first region and a second region that are delineated by a straight line parallel to a short side of the chip card, the first region containing the cut-out zone;   a first slit connecting the cut-out zone to a peripheral edge of the first region;   a second slit opening either onto a peripheral edge of the metal layer or into the cut-out zone, the second slit ending with a closed portion in the second region; and   a second RF antenna electrically insulated from the metal layer and from the first RF antenna and configured to allow coupling to the first RF antenna, the second RF antenna comprising at least one portion of turn located facing the first slit and at least one portion of turn located facing said second slit.   
     
     
         2 . The chip card according to  claim 1 , wherein the second RF antenna comprises:
 a first antenna portion lying facing a peripheral zone of the metal layer, at least one turn of said first antenna portion lying facing the first slit;   a second antenna portion connected to the first antenna portion and arranged at least partially facing the second region of the metal layer, at least one turn of said second antenna portion lying facing, at least partially, the second slit; and   a third antenna portion, electrically connected to the second antenna portion, and lying facing the cut-out zone so as to allow coupling to the first RF antenna,   the first antenna portion being configured to collect an image current induced by first eddy currents flowing on an edge through the metal layer when the chip card is subjected to an electromagnetic field under operating conditions of the chip card, and   the second antenna portion being configured to collect an image current induced by the first eddy currents flowing through the second region of the metal layer when the chip card is subjected to an electromagnetic field under adverse operating conditions corresponding to only some of said operating conditions.   
     
     
         3 . The chip card according to  claim 2 , wherein the adverse operating conditions are conditions under which the chip card is off-centre with respect to an antenna of a device generating said electromagnetic field. 
     
     
         4 . The chip card according to  claim 1 , wherein said second region comprises a special zone for exploitation of eddy currents, said second RF antenna being located facing the second slit in said special zone. 
     
     
         5 . The chip card according to  claim 4 , wherein said special zone for exploitation of the eddy currents is a zone of a surface of the chip card that is subjected to a uniform maximum-strength magnetic field whatever the operating conditions of the chip card. 
     
     
         6 . The chip card according to  claim 4 , wherein said special zone for exploitation of the eddy currents is a disk centred on said chip card and a radius of the special zone corresponds to a radius of an operational volume of said chip card. 
     
     
         7 . The chip card according to  claim 6 , wherein the chip card complies with an EMVCo standard, said special zone for exploitation of the eddy currents being a disk of 25 mm radius centred on said chip card. 
     
     
         8 . A method for manufacturing a chip card of generally rectangular shape from a card body formed at least in part by a metal layer, said metal layer comprising a cut-out zone, said metal layer consisting of a first region and a second region entirely delineated by a straight line parallel to a short side of the chip card, the first region completely containing the cut-out zone and an area of the first region being smaller than an area of the second region, a first slit in the metal layer connecting the cut-out zone to a peripheral edge of the first region and a second slit in the metal layer opening either onto a peripheral edge of the metal layer or into the cut-out zone, the second slit ending with a closed portion in the second region, the method comprising:
 forming, on or in the card body, a first RF antenna in or facing the cut-out zone of the metal layer;   assembling an RF chip with the card body so that the RF chip is electrically connected to the first RF antenna; and   forming, on or in the card body, a second RF antenna so that the second RF antenna is electrically insulated from the metal layer and from the first RF antenna, the second RF antenna being configured to allow coupling to the first RF antenna, the second RF antenna comprising at least one portion of turn located facing the first slit and at least one portion of turn located facing the second slit.   
     
     
         9 . The chip card according to  claim 5 , wherein said special zone for exploitation of the eddy currents is a disk centred on said chip card and a radius of the special zone corresponds to a radius of an operational volume of said chip card. 
     
     
         10 . The chip card according to  claim 9 , wherein the chip card complies with an EMVCo standard, said special zone for exploitation of the eddy currents being a disk of 25 mm radius centred on said chip card. 
     
     
         11 . The chip card according to  claim 2 , wherein said second region comprises a special zone for exploitation of eddy currents, said second RF antenna being located facing the second slit in said special zone. 
     
     
         12 . The chip card according to  claim 11 , wherein said special zone for exploitation of the eddy currents is a disk centered on said chip card and a radius of the special zone corresponds to a radius of an operational volume of said chip card. 
     
     
         13 . The chip card according to  claim 12 , wherein the chip card complies with an EMVCo standard, said special zone for exploitation of the eddy currents being a disk of 25 mm radius centered on said chip card. 
     
     
         14 . The chip card according to  claim 11 , wherein said special zone for exploitation of the eddy currents is a zone of a surface of the chip card that is subjected to a uniform maximum-strength magnetic field whatever the operating conditions of the chip card. 
     
     
         15 . The chip card according to  claim 14 , wherein said special zone for exploitation of the eddy currents is a disk centered on said chip card and a radius of the special zone corresponds to a radius of an operational volume of said chip card. 
     
     
         16 . The chip card according to  claim 3 , wherein said second region comprises a special zone for exploitation of eddy currents, said second RF antenna being located facing the second slit in said special zone. 
     
     
         17 . The chip card according to  claim 16 , wherein said special zone for exploitation of the eddy currents is a disk centered on said chip card and a radius of the special zone corresponds to a radius of an operational volume of said chip card. 
     
     
         18 . The chip card according to  claim 17 , wherein the chip card complies with an EMVCo standard, said special zone for exploitation of the eddy currents being a disk of 25 mm radius centered on said chip card. 
     
     
         19 . The chip card according to  claim 16 , wherein said special zone for exploitation of the eddy currents is a zone of a surface of the chip card that is subjected to a uniform maximum-strength magnetic field whatever the operating conditions of the chip card. 
     
     
         20 . The chip card according to  claim 19 , wherein said special zone for exploitation of the eddy currents is a disk centered on said chip card and a radius of the special zone corresponds to a radius of an operational volume of said chip card.